1. Field
Example embodiments are directed to a method of forming metallic oxide films, for example, a method of forming metallic oxide films using Atomic Layer Deposition.
2. Description of Related Art
Methods of forming thin films, for example, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), and ALD (Atomic Layer Deposition), may be used to form thin films on semiconductor substrates.
Whereas several conventional methods may supply multiple gases at one time, ALD may be used to form thin films by supplying gases in the form of individual pulses at given intervals. For example, a thin film having roughly an atomic thickness may be formed by alternately supplying a source gas and a purge gas, and a reactant gas and a purge gas. The ALD may provide beneficial step coverage and uniformity even on a large substrate. Furthermore, the thickness of the thin film may be adjusted by controlling the number of cycle repetitions.
In addition to conventional ALD, PEALD (Plasma Enhanced Atomic Layer Deposition) may be used for forming thin films by changing a reactant gas into a plasma state. PEALD may be advantageous because of beneficial deposition rates and electrical properties, and may allow deposition of a variety of substances.
In PEALD, plasma power may be supplied to produce a plasma. High frequency power for producing a plasma may be supplied from a high frequency power source through an impedance matching box, for example. Reflected power not absorbed into the plasma may be detected and reflected to the high frequency power source. Accordingly, plasma power may be supplied in consideration of the reflected power.
As the magnitude of reflected power becomes relatively small and/or uniform, it may become easier to control the plasma power. When the magnitude of reflected power becomes relatively large and/or non-uniform, it may be more difficult to control the plasma power, and the plasma production may become unstable.